As this class would be used in other Comparators, we should make this as singleton design pattern. I have just modified this class, so that it can be used in concurrent environments.

Comment From: abhishek-abhi

Hi, @jhoeller please review my PR, please give suggestions and merge this if its okay.

Comment From: snicoll

Thank you for the PR but there is nothing wrong with the current code. Changing the visibility of the default instance to private is a breaking change. Please review the comment I've added to your other PR.